The Helepolis at Rhodes
Height: 130-140ft (40-43m)
Base: 72ft (22m) square
Armament: Lowest floor: 2×180 Iber (82kg) catapults; 1×60 Iber (27kg) catapult 1st floor: 3×60 Iber (27kg) catapults Next five floors: 2×30 Iber (14kg) catapults Top two floors: 2x dart-throwers.
Construction: main beams are fir or pine, wheels and horizontals are oak. All major joints are reinforced with iron plates. To protect the machine from fire-missiles, its exterior is clad with iron plates on 3 sides.
Propulsion: the machine is mounted on eight wheels each 15ft (4’6m) in diameter. It is propelled by a capstan and belt drive, with a suitable mechanical advantage, (manned by roughly 200 men). Additional thrust could be provided from the rear.
Weight: Probably around 150 tons.
Siege towers had existed since Assyrian times. That illustrated is the famous helepolis built by Epimachus of Athens for Demetrius “Poliorcetes” (the Besieger) in 304 BC. This was the largest siege-tower of ancient times and descriptions of it survive in the accounts of Vitruvius, Diodorus, Plutarch and the so-called Athenaeus Mechanicus. Most siege towers were smaller than this gigantic structure and were hide and wool or hide and seaweed covered. Many had drawbridges, but this one apparently did not. In action it was brought up within missile range of the walls, supplying suppressing fire against the defenders. The large stone-thrower could even destroy ramparts and curtain-walls. Once this had been accomplished attackers could bring up battering rams and drills, or undermine the walls. Alternatively an assault could be mounted with ladders, drawbridges sambuca etc.
Heavy artillery catapault of the type probably mounted by Demetrius on his mighty siege engines used in his attack on Rhodes, which is thought to have been launched from Loryma Sound.
In war among the successors of Alexander the Great, Demetrius Poliorcetes, son of Antigonus, seized Cyprus from Ptolemy of Egypt with victory at Salamis (306 bc) then tried to capture Rhodes, which was supported by Ptolemy. Demetrius landed with a massive force and advanced siege equipment, but after two years and costly losses, he could make no impression against heroic defence and withdrew.
Demetrius brought to the siege of Rhodes a vast armament of men and ships. Apart from his own fighting fleet of 200 vessels and his auxiliary fleet of more than 150, he had enlisted the aid of pirate squadrons. One thousand private trading craft also followed him, attracted by the wealth of Rhodes and the prospect of spoil. The whole operation was, in fact, a gigantic piratical enterprise. But Demetrius seems to have felt that it was “a glorious thing to be a pirate king”.
The main harbour at Rhodes, as well as the city, was fortified with towers and walls. Here the Rhodian fleet could safely rest; nor was Demetrius able to prevent ships with supplies from running his blockade. His first concern, therefore, was to capture the harbour. He at once proceeded to build his own harbour alongside, constructing a mole and protecting his seaborne siege operations from counter-attack by means of a floating spiked boom. At the same time, his army ravaged the island and built a huge camp on land adjacent to the city but out of missile range.
In the course of the siege, both sides employed the technical devices we have just described. Mining operations by the besiegers were met by the counter-mines of the besieged. At a fairly early stage, Demetrius’ men secured a footing on the mole of the main harbour, but the Rhodians prevented him from exploiting this bridgehead and he never captured the harbour. Later, as the result of a land attack, he actually penetrated the walls of the city, but the attack was contained by the Rhodians and those who had entered were mostly killed.
The most sensational feature of the siege was Demetrius’ mammoth tower, which was nicknamed the helepolis, “city-taker”, although in the event it failed to take the city. The helepolis tower was based on a huge square grille of timberwork, covering an area of 5,200 square feet (484 sq m). The tower was about 140 feet (90 cubits, 43m) high and the uppermost of its nine storeys was 900 square feet (84 sq m) in area. As a protection against fire, the tower was armoured with iron plates on its three exposed sides; it was mounted on gigantic castors, the wheels of which were themselves plated with iron. The artillery ports of the helepolis were made to open and close by mechanical means and were padded with leather and wool as a protection against the shock of missile attack. Communication with the upper storeys was by means of two staircases, for ascent and descent respectively.
The machine was moved, presumably in relays, by 3,400 specially selected strong men. Some pushed from inside the structure, others behind. Diodorus assures us that the whole monstrous contraption could be rolled in any direction very smoothly. The helepolis was in effect a mammoth tank, far larger than any that have ever been driven by petrol engines. Despite every precaution, however, the Rhodians managed to dislodge some of the tower’s iron plates; when there was a real danger of it being set on fire, Demetrius ordered it to be withdrawn from action.
The entire Greek and Macedonian world, constitutionalists and dynasts alike, sympathized with the Rhodians during the siege. The conflict was, after all, one between law and piracy. Influenced perhaps by the unpopularity of his operations and convinced at last that he could not win, Demetrius came to terms with the Rhodians and went away to look for a war somewhere else. The Rhodians, overjoyed, rewarded the sacrifice of citizens, slaves and resident aliens as they had promised. Demetrius had left his engines strewn around the city and the scrap metal which they yielded provided material for the huge statue which the Rhodians erected at their harbour entrance: the Colossus of Rhodes, one of the Seven Wonders of the World. A prodigy itself, the Colossus was a fitting memorial to a prodigious siege.
During the grueling year-long siege of the island of Rhodes by Demetrius Poliorcetes (“The Besieger”) in 304 BC, both sides hurled resinous missiles—firepots and flaming arrows. On moonless nights during the siege, wrote Diodorus of Sicily, “the fire-missiles burned bright as they hurtled violently through the air.” The morning after a particularly spectacular night attack, Demetrius Poliorcetes had his men collect and count the fire missiles. He was startled by the vast resources of the city. In a single night, the Rhodians had fired more than eight hundred fiery projectiles of various sizes, and fifteen hundred catapult bolts. Rhodes’ resistance was successful, and Poliorcetes withdrew with his reputation tarnished, abandoning his valuable siege equipment. From the sale of his machines, the Rhodians financed the building of the Colossus of Rhodes astride their harbor, one of the Seven Wonders of the Ancient World.
Catapults were also deployed on ships in order to bombard a besieged maritime city, as in the case of Alexander at Tyre in 332, who used his horse transport ships and his triremes to provide firing platforms. Demetrius Poliorcetes’ attacks against Rhodes in 305-4 made effective use of ship-mounted catapults against the city’s harbour areas.
Another cost to Hellenistic warfare that had risen considerably from its classical predecessor was that of siege warfare. As defensive works quickly caught up to the Macedonian advances in siege technology from the midfourth century, so offensive siege weapons had to improve. As witnessed at Demetrius Poliorcetes’ siege of Rhodes from 305 to 304, this now became a business unto itself, and as a business it is likely to have had no small effect upon the economies where production of machines was greatest. Highly experienced and highly expensive scientists and engineers now began to build massive and complex engines in order to topple the walls of Hellenistic cities. As a result of this, defensive works again experienced a technological advancement, with many cities now beginning major fortification projects. More remembered today for his mathematical genius, during his own age the great Archimedes was actually a master of defensive siege warfare, and his devices significantly delayed the Roman capture of Syracuse.